One dead, two injured in west Sydney crash

One person is dead and two more remain in hospital after a car twice veered onto a footpath in Sydney's west before smashing into a pole.

Police say a 91-year-old female pedestrian was struck after a driver mounted a footpath in Greenacre on Thursday morning.

The car then continued down the road about 200m before again veering onto a footpath, striking a 77-year-old male pedestrian who was reportedly sitting on a wall that the driver ploughed through.

The vehicle then crashed into a pole, trapping the 63-year-old female driver for more than an hour before she was eventually prised free and taken to hospital.

The female pedestrian was taken to hospital in a critical condition, but died on Thursday afternoon.

The driver remains in a critical condition while the male pedestrian's condition is serious, a Liverpool Hospital spokeswoman told AAP on Thursday night.